A current controlled level shifter comprises an input stage, which produces a first and a second control current on the basis of an input signal, and a shifter stage, which takes the control currents and produces an output signal which is dependent on the input signal but which takes a different potential than the input signal as a reference.
In such a level shifter, the control currents are flowing permanently, not just for a respective time after a level change in the input signal. This means that—unlike in the case of edge controlled level shifters—no refresh pulses produced at regular intervals of time are required.
In the case of a current controlled level shifter, there is a delay between a level change in the input signal and a corresponding level change in the output signal, with the delay being dependent on the amplitude of the control currents. The delay time is caused by parasitic capacitances, which need to have their charges reversed before a level change in the output signal. In this case, the delay time is shorter the greater the amplitudes of the control currents. However, the power loss arising also increases as the amplitude of the control currents increases.